[PATCH tip/core/rcu 03/21] rcutorture: Add cond_resched() to forward-progress free-up loop

From: Paul E. McKenney
Date: Thu May 30 2019 - 11:23:38 EST


The rcu_torture_fwd_prog_cbfree() function frees callbacks used during
rcutorture's call_rcu() forward-progress test, but does so in a tight
loop. This could cause problems given a very long list of callbacks to be
freed, and actual testing produces lists with as many as 25M callbacks.
This commit therefore adds a cond_resched() to this loop. While in
the area, this commit also rearranges the lock releases to look a bit
more sane.

Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxx>
---
kernel/rcu/rcutorture.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index efaa5b3f4d3f..7906ba2d9dad 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -1674,16 +1674,18 @@ static unsigned long rcu_torture_fwd_prog_cbfree(void)
for (;;) {
spin_lock_irqsave(&rcu_fwd_lock, flags);
rfcp = rcu_fwd_cb_head;
- if (!rfcp)
+ if (!rfcp) {
+ spin_unlock_irqrestore(&rcu_fwd_lock, flags);
break;
+ }
rcu_fwd_cb_head = rfcp->rfc_next;
if (!rcu_fwd_cb_head)
rcu_fwd_cb_tail = &rcu_fwd_cb_head;
spin_unlock_irqrestore(&rcu_fwd_lock, flags);
kfree(rfcp);
freed++;
+ cond_resched();
}
- spin_unlock_irqrestore(&rcu_fwd_lock, flags);
return freed;
}

--
2.17.1